Having less-than-perfect vision may be the secret of being a great artist, scientists have revealed.

A team from Harvard Medical School say the Dutch master Rembrandt may have had extropia - where one eye looks outwards.

The scientists analysed his self-portraits and found one eye looked straight ahead, while the other looked outward.

Writing in the New England Journal of Medicine, they say this may have helped him perceive the world as a flat image.

Art teachers often instruct students to close one eye in order to flatten what they see

Margaret Livingstone, Harvard Medical School

The perfect alignment of the eyes, called stereoscopic vision, allows people to see in three dimensions.

But neurobiologist Margaret Livingstone, who carried out the study, suggests this could be a hindrance to an artist trying to depict a 3D scene on a flat canvas.

She said: "Art teachers often instruct students to close one eye in order to flatten what they see."

"Therefore, stereoblindness might not be a handicap -and might even be an
asset - for some artists."

'Benefit'

Dr Livingstone and her colleagues analysed 24 oil paintings and 12 etchings in which the 17th century master Rembrandt van Rijn depicted himself.

In all but one painting, the eye on the right of the painting looked straight ahead, and the one on the left looked outwards.

They suggest this means it was his left eye which was affected, because the paintings would have been done by looking in a mirror.

In the etchings, the opposite eye appeared to be the one which was misaligned, but the researchers say left and right are reversed in an etching, which is made by scratching lines on a metal plate and using the plate to make a print.

They say having a lazy eye, also known as extropia, can be a benefit to an artist.

"We examined a number of self-portraits of Rembrandt, an artist known for his astute powers of observation, and noticed that many of them show his eyes are exotrophic."

They say the errant eye appears to be gazing around 10 degrees off-centre.

Dr Livingstone told Reuters news agency: "It illustrates that disabilities are not always disabilities. They may be assets in another realm."